[Fwd: Re: Op Amp pinouts was Re: [sdiy] more LM3900 stuff]

[Seb Francis]

This reply was meant for the list I think ...

-------- Original Message --------
Subject: 	Re: Op Amp pinouts was Re: [sdiy] more LM3900 stuff
Date: 	Tue, 17 Jan 2006 13:54:49 -0600
From: 	Pat Kammerer <spivkurl at wearerecords.com>
Reply-To: 	Pat Kammerer <spivkurl at wearerecords.com>
To: 	Seb Francis <seb at burnit.co.uk>
References: 	<20060113225527.54469.qmail at web51005.mail.yahoo.com> 
<200601151622.26508.rtellason at blazenet.net> 
<008901c61a1d$6a773990$0200a8c0 at jhsilent> 
<200601151700.57842.rtellason at blazenet.net> 
<009901c61a23$34cbd930$0200a8c0 at jhsilent> 
<43CAED40.BE1D7450 at prodigy.net> <43CAF1A4.4070204 at burnit.co.uk>



----- Original Message -----
From: Seb Francis <seb at burnit.co.uk>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, January 15, 2006 7:06 PM
Subject: Re: Op Amp pinouts was Re: [sdiy] more LM3900 stuff


>
> >>e transistor circuits or NE5532 or AD275 for "demanding" audio
> >>circuits,
> >>
> >>
> >
> >5532 is pretty demanding of power supply current, and low input
> >impedance
> >for best results. Have not tried the AD275... whats it like ???
> >
>
> Maybe JH means the Analog Devices OP275 ?  I've seen this one used in
> many high-end audio circuits.
>
>  From the datasheet..
> "The OP275 is the first amplifier to feature the Butler Amplifier front
> end. This new front end design combines both bipolar and JFET
> transistors to attain amplifiers with the accuracy and low noise
> performance of bipolar transistors, and the speed and sound quality of
> JFETs. Total Harmonic Distortion plus Noise equals that of previous
> audio amplifiers, but at much lower supply currents."
>
> Seb

I find that at low supply voltages the OP275 distorts undesirably.  I find
that a much better alternative is the OP270.